A method for surface passivation of perovskite films in high-efficiency solar cells

Abstract

The invention discloses a method for passivating the surface of a perovskite film in a high-efficiency solar cell, wherein a DMF solution containing thiophene-2-formamidine hydroiodic acid (ThFAI) is used to modify a buried layer of a perovskite solar cell, and the DMF solution containing thiophene-2-formamidine hydroiodic acid is spin-coated on a hole transport layer PTAA, and then a perovskite layer is prepared by a one-step method. The DMF solution containing thiophene-2-formamidine hydroiodic acid can effectively improve the wettability of the perovskite solution on the PTAA hole transport layer, thereby facilitating better spreading of the perovskite solution on the PTAA dense layer, thereby obtaining a perovskite film with a larger grain size and less defect concentration, and finally obtaining a perovskite solar cell with higher photoelectric performance.

Description

Technical Field

[0001] The invention relates to a method for preparing a perovskite thin film layer of a perovskite solar cell, and in particular to a method for passivating the surface of a perovskite thin film in a high-efficiency solar cell. Background Art

[0002] Perovskite solar cells have emerged among many new thin-film solar cells, and their photoelectric conversion efficiency has been continuously developed from 3.8% in 2009 to more than 25%. This is mainly due to the following advantages of perovskite solar cells: strong light absorption, high carrier mobility, simple structure, simple preparation process and low cost. However, interface recombination and defect concentration of perovskite films will inhibit the extraction of carriers.

[0003] Therefore, modifying the buried layer and passivating the defects of the perovskite film is conducive to the preparation of higher quality perovskite films, which can ultimately improve the photoelectric conversion efficiency of perovskite solar cells. Summary of the invention

[0004] The purpose of the present invention is to provide a method for passivating the surface of a perovskite film in a high-efficiency solar cell to achieve efficient carrier transport and improve the photoelectric conversion efficiency of the perovskite solar cell. The present invention has the advantages of simple preparation process, low cost, and easy operation.

[0005] The method for passivating the surface of a perovskite film in a high-efficiency solar cell of the present invention is to modify the buried layer of the perovskite solar cell with a DMF solution containing thiophene-2-carboxamidine hydroiodic acid (ThFAI).

[0006] Specifically, a DMF solution containing thiophene-2-carboxamidine hydroiodic acid is spin-coated on the hole transport layer PTAA, and then a perovskite layer is prepared by a one-step method. The steps include:

[0007] Step 1: Place the cleaned ITO substrate into a UV ozone cleaning machine for ozone treatment for 20 to 30 minutes;

[0008] Step 2: Weigh 1.5-2 mg of PTAA and dissolve it in chlorobenzene, add a magnetic stirrer and stir for 2-3 hours; spin-coat the PTAA solution at 3000-6000 rpm for 30 seconds; anneal after the spin coating to obtain a hole transport layer PTAA layer;

[0009] Step 3: Take 5-50 mg of thiophene-2-carboxamidine hydroiodic acid and dissolve it in 1 mL of DMF solvent, stir it magnetically for 2-5 hours, and filter it to obtain a DMF solution containing thiophene-2-carboxamidine hydroiodic acid; dynamically spin-coat 50-100 μL of the DMF solution containing thiophene-2-carboxamidine hydroiodic acid on the hole transport layer PTAA layer;

[0010] More specifically, for example, 50 mg of thiophene-2-carboxamidine hydroiodic acid is dissolved in 1 mL of DMF, and then a magnetic stirrer is added and stirred for 2 to 3 hours. The solution is then filtered, and 100 μL of thiophene-2-carboxamidine hydroiodic acid solution is taken and dynamically spin-coated onto the PTAA layer at a rotation speed of 4000 to 5000 rpm.

[0011] Step 4: Take 600 μL of DMSO and 2400 μL of DMF and mix and stir for 10-12 hours to obtain a mixed solution of DMSO and DMF; take 208.3 mg of FAI and 587.79 mg of PbI 2 Dissolve in 1 mL of DMSO and DMF mixed solution and stir for 4-5 h to obtain solution ①; take 79.8 mg MABr and 275.3 mg PbBr 2 Dissolve in 0.5 mL of a mixed solution of DMSO and DMF and stir for 4-5 h to obtain solution ②; Take 77.94 mg of CsI and dissolve it in a DMSO solution and stir for 4-5 h to obtain solution ③;

[0012] Step 5: Take 440 μL of solution ①, 66 μL of solution ② and 44 μL of solution ③, mix and stir for 4 to 5 hours; use a one-step spin coating method to spin coat the perovskite solution on the PTAA dense layer, and the perovskite film can be obtained after annealing.

[0013] Further:

[0014] In step 2, the annealing temperature of the hole transport layer is 80-100°C.

[0015] In step 3, the concentration of the DMF solution containing thiophene-2-carboxamidine hydroiodic acid is 5 to 50 mg / mL, preferably 5 to 20 mg / mL.

[0016] In step 3, the rotation speed is controlled at 3000 rpm to 6000 rpm during dynamic spin coating of the DMF solution containing thiophene-2-carboxamidine hydroiodic acid, and the spin coating time is between 10 s and 25 s.

[0017] In step 5, the annealing temperature is 100-105° C., and the annealing time is 30-40 min.

[0018] In inverse perovskite solar cells, PTAA is a commonly used hole transport layer. However, since the wettability of the perovskite solution on the PTAA layer is poor, in order to modify the buried layer of the perovskite, the present invention modifies it by using a conjugated organic molecule thiophene-2-carboxamidine hydroiodic acid, which can improve the wettability of PTAA and modify the buried layer of the perovskite.

[0019] The DMF solution of thiophene-2-carboxamidine hydroiodic acid can effectively improve the wettability of the perovskite solution on the PTAA hole transport layer, which is conducive to better spreading of the perovskite solution on the PTAA dense layer, thereby obtaining a perovskite film with a larger grain size and less defect concentration, and finally obtaining a perovskite solar cell with higher photoelectric performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a scanning electron microscope image of a standard perovskite film that has not been modified with thiophene-2-carboxamidine hydroiodic acid;

[0021] Figure 2 This is a scanning electron microscope photo of a perovskite film modified with thiophene-2-carboxamidine hydroiodic acid;

[0022] Figure 3 is the contact angle diagram of the standard PTAA film that has not been treated with thiophene-2-carboxamidine hydroiodic acid;

[0023] Figure 4 This is the contact angle diagram of the PTAA film treated with thiophene-2-carboxamidine hydroiodic acid;

[0024] Figure 5 IV curves of a standard battery and a battery passivated with thiophene-2-carboxamidine hydroiodic acid;

[0025] Figure 6 It is a schematic diagram of the structure of a standard battery;

[0026] Figure 7 Schematic diagram of the battery structure treated with thiophene-2-carboxamidine hydroiodic acid. DETAILED DESCRIPTION

[0027] In inverse perovskite solar cells, PTAA is a commonly used hole transport layer. However, since the wettability of the perovskite solution on the PTAA layer is poor, in order to modify the buried layer of the perovskite, the present invention modifies it by using a conjugated organic molecule thiophene-2-carboxamidine hydroiodic acid, which can improve the wettability of PTAA and modify the buried layer of the perovskite.

[0028] Example 1: Preparation of Thiophene-2-Carboxamidine Hydroiodic Acid Solution

[0029] 1. Dissolve 10 mg of thiophene-2-carboxamidine hydroiodic acid powder in 1 mL of DMF and stir with a magnetic stirrer for 2 to 3 hours;

[0030] 2. Use a filter head to filter the stirred thiophene-2-carboxamidine hydroiodic acid solution to obtain the thiophene-2-carboxamidine hydroiodic acid solution required for the experiment.

[0031] Example 2: Preparation of standard perovskite solar cell devices and preparation of modified perovskite solar cell devices

[0032] According to the following steps, the Figure 6 and Figure 7 Perovskite solar cell devices:

[0033] 1. Cleaning of ITO glass substrate: ultrasonically clean with deionized water, acetone and ethanol for 15 to 20 minutes, and then blow dry with an air gun immediately;

[0034] 2. Treatment of ITO glass substrate: UV treatment of ITO substrate for 20 to 30 minutes;

[0035] 3. Preparation of hole transport layer: 40-50 μL of PTAA precursor solution was dripped onto the ITO conductive substrate and spin-coated at 4000-5000 rpm for 20-30 seconds. After the spin coating, annealing was performed on a heating table at 80-100°C for 10-15 minutes to form a PTAA layer.

[0036] 4. Standard perovskite film production: 208.3 mg FAI and 587.79 mg PbI 2 Dissolve in 1 mL of DMSO and DMF mixed solution and stir for 4-5 h (solution ①); take 79.8 mg MABr and 275.3 mg PbBr 2 Dissolve in 0.5mL of DMSO and DMF mixed solution and stir for 4-5h (solution ②); Take 77.94mg CsI and dissolve in DMSO solution and stir for 4-5h (solution ③), take 440μL solution ①, 66μL solution ② and 44μL solution ③ and mix and stir for 4-5h, then take 50-100μLDMF solution and dynamically spin-coat it on the PTAA layer at a speed of 4000-5000rpm, then take 50-80μL perovskite precursor solution and drop it on ITO, and spin-coat it at a speed of 1000-1200rpm for 10-12s, then spin-coat it at a speed of 4000-5000rpm for 25-30s, add anti-solvent at the countdown of 4-6 seconds, and place it on a heating table at 100-105℃ for annealing for 30-40min;

[0037] 5. Preparation of perovskite film modified with thiophene-2-carboxamidine hydroiodic acid: 50-100 μL of thiophene-2-carboxamidine hydroiodic acid solution was dynamically spin-coated on the PTAA layer at a speed of 4000-5000 rpm, and then 50-80 μL of perovskite precursor solution was dropped on the ITO, and spin-coated at a speed of 1000-1200 rpm for 10-12 s, and then spin-coated at a speed of 4000-5000 rpm for 25-30 s. Anti-solvent was added at the countdown of 4-6 seconds, and the film was placed on a heating table for annealing at 100-105°C for 30-40 min;

[0038] 6. Preparation of electron transport layer 1: Dissolve 25 mg of PCBM in chlorobenzene, heat and stir at 50-60°C for 1.5-2 hours, then drop 40-50 μL of PCBM solution on ITO and spin coat at 2500-3000 rpm for 20-30 seconds, then place on a heating table at 70-80°C for annealing for 10-15 minutes;

[0039] 7. Preparation of the second electron transport layer: Take excess BCP and dissolve it in methanol, heat and stir at 30-40℃ for 6h, let it stand for 12-18h, then take 60-70 saturated BCP solution, dynamically spin-coat it at 6000-6500rpm for 25-30s, then place it on a heating table and anneal it at 70-80℃ for 10-15min;

[0040] 8. Preparation of electrode: Deposit 60-80 nm Ag electrode by thermal evaporation under vacuum.

[0041] The efficiency of the prepared standard perovskite solar cell device is 15.9%, and the efficiency of the perovskite solar cell device modified with thiophene-2-carboxamidine hydroiodic acid is 18.6%.

[0042] Figure 1 This is a scanning electron microscope image of an unmodified standard perovskite film, showing its small grain size;

[0043] Figure 2 This is a scanning electron microscope photo of the perovskite film modified with thiophene-2-carboxamidine hydroiodic acid, showing that its grain size is significantly increased;

[0044] Figure 3 This is the contact angle diagram of the untreated standard PTAA film, with a contact angle as high as 100°;

[0045] Figure 4 This is the contact angle diagram of the PTAA film treated with thiophene-2-carboxamidine hydroiodic acid. Its contact angle is significantly reduced to only 79°, and its wettability is significantly improved;

[0046] Figure 5 IV curves of standard cells and perovskite solar cells after thiophene-2-carboxamidine hydroiodic acid modified buried layer.

Claims

1. A method for surface passivation of a perovskite film in a high-efficiency solar cell, characterized in that: The buried layer of the perovskite solar cell is modified with a DMF solution containing thiophene-2-carboxamidine hydroiodic acid, the DMF solution containing thiophene-2-carboxamidine hydroiodic acid is spin-coated on the hole transport layer PTAA, and then the perovskite layer is prepared by a one-step method; The steps include: Step 1: Place the cleaned ITO substrate into a UV ozone cleaning machine for ozone treatment for 20-30 minutes; Step 2: Weigh 1.5-2 mg of PTAA and dissolve it in chlorobenzene, add a magnetic stirrer and stir for 2-3 hours; spin-coat the PTAA solution at 3000-6000 rpm for 30 seconds; anneal after the spin coating to obtain a hole transport layer PTAA layer; Step 3: dissolving thiophene-2-carboxamidine hydroiodic acid in DMF solvent, stirring magnetically for 2-5 h, filtering to obtain a DMF solution containing thiophene-2-carboxamidine hydroiodic acid; dynamically spin-coating the DMF solution containing thiophene-2-carboxamidine hydroiodic acid on the hole transport layer PTAA layer; Step 4: Take 600 μL DMSO and 2400 μL DMF and mix and stir for 10-12 hours to obtain a DMSO and DMF mixed solution; take 208.3 mg FAI and 587.79 mg PbI2 and dissolve them in 1 mL of DMSO and DMF mixed solution and stir for 4-5 hours to obtain solution ①; take 79.8 mg MABr and 275.3 mg PbBr2 and dissolve them in 0.5 mL of DMSO and DMF mixed solution and stir for 4-5 hours to obtain solution ②; take 77.94 mg CsI and dissolve it in DMSO solution and stir for 4-5 hours to obtain solution ③; Step 5: Take 440 μL of solution ①, 66 μL of solution ② and 44 μL of solution ③ and mix and stir for 4-5 hours; use a one-step spin coating method to spin-coat the perovskite solution on the PTAA dense layer, and after annealing, the perovskite film can be obtained; In step 3, the concentration of the DMF solution containing thiophene-2-carboxamidine hydroiodic acid is 5-50 mg / mL; the rotation speed is controlled at 3000 rpm-6000 rpm during dynamic spin coating of the DMF solution containing thiophene-2-carboxamidine hydroiodic acid, and the spin coating time is between 10 s and 25 s.

2. The method according to claim 1, characterized in that: In step 2, the annealing temperature of the hole transport layer is 80-100°C.

3. The method according to claim 1, characterized in that: The concentration of the DMF solution containing thiophene-2-carboxamidine hydroiodide is 5-20 mg / mL.

4. The method according to claim 1, characterized in that: In step 5, the annealing temperature is 100-105°C, and the annealing time is 30-40 min.

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